-3scale, nor is there uniformity in the distribution of these materials in the animal, and in the plant, or in the stream, or on the ground, or in the air, I have discussed this a little because you will be dealing with some animals and same plant materials, and you may be struck with the fact that your information is not comparable to that of your neighbor because you are using two different animals. That is why so much of the distribution data is plotted on the basis of percentage, The body is very much like an engine going at a modere ate rate of speed, and you have to nick off your sampling while the engine is working because the biological processes are working and you can't stop them. If you stop them you get an abnormal result. The problem is always to obtain your data without your method of sampling causing distortions. Of course by eriment you do change the situation from time to time in order to bring out certain deviations which give you a clue or might give you a clue to what the normal physiology is. nuthis concept cf the non-static position of biological ateriate is a little bit new to biolosists in general, although many will not admit that it has crept upon them from the period of the first use of isotopes. Those of you who know ruch about the field know that before the war, a good deal of work was being done with isotopes, and a great deal of confusion resulted.